Particle placing system

ABSTRACT

A particle placing system wherein particulate material is placed in or on a softenable layer by pressing a donor uniformly coated with particulate material, alternatively, at least partially in softenable material against a free surface of a softenable layer or a substrate of a migration imaging member.

United States Patent [191 Amidon et al.

[451 7 Oct. 8, 1974 1 PARTICLE PLACING SYSTEM [751 Inventors: Alan B.Amidon, Penfield; William L. Goffe, Webster, both of NY.

[73] Assignee: Xerox Corporation, Rochester, NY.

[22] Filed: July 13, 1972 [211 App]. No.: 271,439

Related US. Application Data [63] Continuation of Ser. No. 685,536, Nov.24, 1967,

abandoned.

[52] US. Cl 117/201, ll7/l7.5, 96/1 R, 96/1 E [51] Int. Cl G03g 13/00[58] Field of Search 117/16, 17, 9, 17.5, 201; 96/1 R, 1, E

[56] References Cited UNITED STATES PATENTS 4/1933 Cutler 118/106Middleton; 96/1 2,924,519 2/1960 Bertelsen 96/1.4 3,054,716 9/1962Bergstein 117/64 3,264,132 8/1966 Merill 117/31 3,266,932 8/1966 Anolick117/62 3,318,697 2/1967 3,520,681 7/1970 Goffe 96/1 PrimaryExaminerRalph S. Kendall Assistant Examiner-Michael F. Esposito 57ABSTRACT A particle placing system wherein particulate material isplaced in or on a softenable layer by pressing a donor uniformly coatedwith particulate material, a1- ternatively, at least partially insoftenable material against a free surface of a softenable layer or asubstrate of a migration imaging member.

6 Claims, 6 Drawing Figures PATENTED 0m 8 I974 3. 840.397

Fl 0. IA FIG. 1,9

[ HI I FIG. 1C FIG. 10

0000 no I Lab/@136 FIG. 2

PARTICLE PLACING SYSTEM This is a continuation of copending applicationSer. No. 685,536, filed Nov. 24, 1967 now abandoned.

BACKGROUND OF THE INVENTION This invention relates in general toimaging, and more specifically to a new process of making a particlemigration imaging member.

There has recently been developed a migration imaging system capable ofproducing high quality images of high density, continuous tone, and highresolution, an embodiment of which is described in copending applicationSer. No. 460,377, filed June 1, 1965 now US. Pat. No. 3,520,681.Generally, according to an embodiment thereof, an imaging membercomprising a conducting substrate with a layer of softenable (hereinalso intended to include soluble) material, containing photosensitiveparticles overlying the conductive substrate is imaged in the followingmanner: a latent image is formed on the member, for example, byuniformly electrostatically charging and exposing it to a pattern ofactivating electromagnetic radiation. The imaging member is thendeveloped by exposing it to a solvent which dissolves only thesoftenable layer. Thephotosensitive particles which have been exposed toradiation migrate through the softenable layer as it is softened anddissolved, leaving an image of migrated particles corresponding to theradiation pattern of an original, on the conductive substrate. The imagemay then be fixed to the substrate. Those portions of the photosensitivematerial which do not migrate to the conductive substrate may be washedaway by the solvent with the softenable layer. As disclosed therein, byother developing techniques, the softenable layer may at least partiallyremain behind on the substrate.

For some preferred photosensitiveparticles, for example those comprisingamorphous selenium, the image produced by the above process is anegative of a positive original, i.e., the photosensitive particlesmigrate in the imagewise illuminated areas.

However, by certain process step sequences and member configurations,positive to positive imaging may be accomplished, i.e., thephotosensitive particles.

migrate in the imagewise unexposed areas. For example, see copendingapplications Ser. Nos. 634,757 and 642,828, filed, Apr. 28, 1967 andJune 1, 1967, respectively.

In general, three basic imaging members may be used: a layeredconfiguration which comprises a substrate coated with a layer ofsoftenable material, and a fracturable and preferably particulate layerof photosensitive material at or embedded nearthe upper surface of thesoftenable layer; a binder structure in which the photosensitiveparticles are dispersed in the softenable layer which overcoats asubstrate; and an overcoated structure in which a substrate isovercoated with a layer of softenable material followed by an overlayerof photosensitive particles and a second overcoating of softenablematerial which sandwiches the photosensitive particles. Fracturablelayer or material as used herein, is intended to mean any layer ormaterial which is capable of breaking up into discrete particles of thesize of an image element or less during development and permittingportions to migrate towards the substrate in image configuration.

This imaging system generally comprises a combination of process stepswhich includes forming a latent image and developing with a solventliquid or vapor, or

.heat or combinations thereof to render the latent image visible. Incertain methods of forming the latent image, non-photosensitive orinert, fracturable and particulate layers and material may be used toform images as described in copending application Ser. No. 483,675,filed Aug. 30, 1965, wherein a latent image is formed by a wide varietyof methods including charging in image configuration through the use ofa mask or stencil or first forming such a charge pattern on a separatephotoconductive insulating layer according to conventional xerographicreproduction techniques and then transferring this charge pattern to themembers hereof by bringing the two layers into very close proximity andutilizing breakdown techniques as described, for example, in Carlson US.Pat. No. 2,982,647 and Walkup US. Pat. No. 2,825,814 and 2,937,943; Inaddition, charge patterns conforming to selected, shaped, electrodes orcombinations of electrodes may be formed by the TESI dischargetechniques as more fully described in Schwertz US. Pat. No. 3,023,731and 2,919,967 or by techniques described in Walkup US. Pat. No.3,001,848 and 3,001,849, as well as by electron beam recordingtechniques, for example, as described in Glenn U.S'. Pat.'No. 3,113,179.

In another variation 'of this imaging system an image is formed by theselective disruption of a particulate material overlying'or in anelectrostatically'deformable, or wrinkable film or layer. This variationdiffers from the system described above in that the softenable layer isdeformed in conjunction with a disruption of the particulate material asdescribed more-fully in copending application Ser. No. 520,423, filedJan. 13, 1966, now abandoned.

The characteristics. of the images produced by this new system aredependent on such process steps as charging, exposure, and development,as well as the particular combination of process steps. High density,continuous tone and high resolution are some of the imagecharacteristics possible. The image is generally characterized as afixed or unfixed particulate image with or without a portion of thesoftenable layer and unmigrated portions of the fracturable layer lefton the imaged member, which can be used in a number of applications suchas microfilm, hard copy, optical masks, and stripout applications usingadhesive materials.

When using the layered imaging member, i.e., where basically the membercomprises a substrate, a softenable layer and an overcoating of aparticulate material near the free surface of the softenable layer, itis preferable in order to form uniform images that the particulatematerial be uniformly deposited over the entire imageable surface of themember. It is also preferred to have the particulate material adheresufficiently to or be sufficiently embedded inthe soluble or softenablelayer so that the imaging member may be conveniently handled and storedprior to processing.

As disclosed in aforementioned copending application Ser. No. 460,377,now US. Pat. No. 3,520,681, two methods of depositing the particulatematerial which reasonably satisfy the requirements of uniformity andstability of the particulate layer are vacuum deposition techniques andcascade techniques where the particulate material is mixed with largercarrier beads for example of the type used in xerography and poured orcascaded over the free surface of the soluble or softenable layer.

Each of these techniques has certain limitations. For example, vacuumevaporation works only for some types of particulate material, requiresa vacuum and requires careful control of substrate temperature and rateof evaporation to obtain optimum results. The cascade technique mayproduce static electricity effects due to interaction of the carrierbeads with the particulate material, and in many applications requiresmore than one cascade to deposite particulate material to sufficientthickness, may be humidity sensitive, may be slow and cumbersome and issometimes difficult to control.

Also, im making binder type imaging members typically comprising a layerof softenable material containing dispersed particles, on a substrate,it is found that normally advantageous modes of forming the particlecontaining softenable layer, which employ coating of a dispersioncomprising particles and softenable material in a liquid solvent vehiclemay attack or degrade certain substrates especially where such substratematerials are soluble in the solvent used in the coating dispersion.

Thus, there is a continuing need for a better system for concentrating agreater amount of particulate material near the free surface of thesoftenable layer and for fabricating binder type migration imagingmembers.

SUMMARY OF THE INVENTION satisfies the above noted wants.

It is a further object of this invention to provide a system of placingparticulate material in or on a softenable layer which does not requirea vacuum.

It is a further object of this invention to provide a system of placingparticulate material in or on a softenable layer which produces nostatic electricity effects.

It is a still further object of this invention to provide a system ofplacing particulate material in or on a softenable layer which producesbetter uniformity and thickness control of the particulate material.

It is a still further object of this invention to provide a system ofplacing particulate material in or on a softenable layer which producesa very dense concentration of particulate material contiguous thesurface of said layer.

It is a still further object of this invention to produce stable imagingmembers which may be handled and stored.

It is a still further object of this invention to provide a system forplacing particulate material in or on a softenable layer which lendsitself to mass production techniques.

It is a still further object of this invention to provide a system offabricating a binder migration imaging member which does not necessitatecoating a dispersion directly on said membe'rs substrate.

The foregoing objects and others are accomplished in accordance withthis invention by providing a system of placing particulate material inor on a softenable layer by pressing a donor uniformly coated withparticulate material alternatively, at least partially in softenablematerial against the free surface of a softenable layer or a substrateof a migration imaging member.

BRIEF DESCRIPTION OF THE DRAWINGS according to this invention.

FIG. 2 is a partially schematic illustration of an embodiment ofapparatus for continuously accomplishing the placing of particlesaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1A, thereis shown layered type migration imaging member 10 according to thisinvention comprising substrate 11, electrically insulating softenablelayer 12 which contains contiguous its upper surface a fracturable layerof particulate photosensitive material l3.-

Substrate 11 may be electrically conductive or insulating; Conductivesubstrates generally facilitate the chargingor sensitizationof themember according to the inventionand typically maybe of copper, brass,nickel, zinc,'chromium, stainless steel, conductive plastics andrubbers, aluminum, steel, cadmium, silver and gold. The substrate maybein any suitable form such as a metallic strip, sheet, plate, coil,cylinder, drum, endless belt, moebius strip or the like. If desired, theconductive substrate may be coated on an insulator such as paper, glassor plastic. Examples of this type of substrate are a substantiallytransparent tin oxide coated glass available under the trademark NESAfrom the Pittsburgh Plate Glass Co., aluminized polyester film, thepolyester film available under the trademark Mylar from DuPont, or Mylarcoated with copper iodide.

Electrically insulating substrates may also be used which opens up awide variety of film formable materi als such as plastics for use assubstrate 11.

Softenable layer 12 may be any suitable material which is soluble orsoftenable in a solvent liquid or vapor or heat or combinations thereofand in addition is substantially electrically insulating during thelatent image forming and developing steps hereof. Typical materialsinclude Staybelite Ester 10, a partially hydrogenated rosin ester, ForalEster, a hydrogenated rosin triester, and Neolyne 23, an alkyd resin,all from Hercules Powder Co.; SR type silicone resins available fromGeneral Electric Corporation; Sucrose Benzoate, Eastman Chemical;Velsicol X-37, a polystyreneolefin copolymer from Velsicol ChemicalCorp.; Hydrogenated Piccopale 100, a highly branched polyolefin,Piccotex 100, polystyrene-vinyl toluene copolymer, Piccolastic A--75,'and 125, all polystyrenes, Piccodiene 2215, a polystyreneolefincopolymer, all from Pennsylvania Industrial Chemical Corp.; Araldite6060 and 6071, epoxy resins from Ciba; R506lA, a phenylmethyl siliconeresin, from Dow Corning; Epon 1001, a bisphenol A-epichlohydrin epoxyresin, from Shell Chemical Corp.; and PS-Z, PS-3, both polystyrenes, andET693, a phenol-formaldehyde resin, from Dow Chemical; acustomsynthesized copolymer of styrene and hexylmethacrylate, a customsynthesized polydi- The above group of materials is not intended to belimiting, but merely illustrative of materials suitable for softenablelayer 12. The softenable layer may be of any suitable thickness, withthicker layers generally requiring a greater charge potential forimaging. In general, thicknesses from about V2 to about 16 microns havebeen found to be preferred with a thickness from about 1 to about 4microns being found to be optimum. Layer 12 may also be of multilayerconstruction, with layers of different softenable materials.

' The material comprising particles 13, portions of which migrate to thesubstrate during image formation, may comprise any suitablephotosensitive fracturable material. While it is preferred for images ofhighest resolution and density that the fracturable material beparticulate, and preferably with an average particle size from about0.01 to about 2.0 microns, it may comprise any continuous orsemi-continuous, such as a swiss cheese pattern, fracturable layer whichis capable of breaking upduring the development step and permittingportions to migrate to the substrate in image configuration.

Photosensitive materials comprising amorphous selenium, for example,amorphous selenium or amorphous selenium alloyed with arsenic,tellurium, antimony, bismuth, etc., or amorphous selenium or an alloythereof doped with a halogen and those comprising phthalocyanineparticles, for example, as listed in copending application Ser. No.375,191, filed June 15, 1964 and including the new X-form metal-freephthalocyanine produced as described in Byrne, et al, U.S. Pat. No.3,357,989 are preferred photosensitive materials because of theirability to form uniform particle layers according to this invention andtheir ability to be optically imaged to form high quality migrationimages.

However, any suitable photosensitive fracturable material may be usedherein. Typical such materials include inorganic or organicphotoconductive insulating materials.

Typical inorganic photoconductors include amorphous selenium; amorphousselenium alloyed with arsenic, tellurium, antimony or bismuth, etc.;amorphous selenium or its alloys doped with halogens; cadmium sulfide,zinc oxide, cadmium sulfoselenide, cadmium yellows such as Lemon Cadmiumyellow X2273 from Imperial Color and Chemical Dept. of Hercules PowderCo., and many others. Middleton et al, U.S. Pat. No. 3,121,006 liststypical inorganic photoconductive piigments. Typical organicphotoconductors include azo dyes such as Watchung Red B, a barium saltof 1- (4-methyl-5'-chloro-azobenzene-2-sulfonic acid)-2-hydrohydroxy-3-napthoic acid, C. I. No. 15865, and Monastral Red B, bothavailable from DuPont; Indofast double scarlet toner, a Pyranthrone-typepigment available from Harmon Colors; quindo magenta RV6803, aquinacridone-type pigment available from Harmon Colors; Cyan Blue, GTNF,the beta form of copper phthalocyanine, C. I. No. 74160, available fromCollway Colors; Monolite Fast Blue GS, the alpha form of metal-freephthalocyanine, C. I. No. 74100, available from Arnold Hoffman Co.;commercial indigo available from National Aniline Division of AlliedChemical Corp.; yellow pigments prepared as disclosed in Weinberger U.S.Pat. No. 3,447,922 or as disclosed in Weinberger U.S. Pat. No.3,402,177, X-form metal-free phthalocyanine prepared as disclosed inByrne, et al, U.S. Pat. No- 3,357,989, quinacridonequinone from DuPont,sensitized polyvinyl carbazole Diane Blue, 3,- 3'-methoxy-4,4-diphenyl-bis (1" azo-2" hydroxy-3"- naphthanilide), C. I. No. 21180, availablefrom Harmon Colors; and Algol G. C. l,2,5,6-di (D,D'-diphenyl)-thiazole-anthraquinone, C. 1. No. 67300, available fromGeneral Dyestuffs and mixtures thereof. The above list of organic andinorganic photoconduc-v tive photosensitive materials is illustrative oftypical materials, and should not be taken as a complete listing ofphotosensitive materials.

The thickness of the fracturable layer in the layered type configurationof FIG. 1A is generally preferably from about 0.01 to about 2.0 micronsalthough 5 micron layers have been found to give good results for somematerials. A more detailed description of the layered configurationimaging member may be found in copending application Ser. No. 635,256,filed May 1, 1967 In addition to the configuration shown in FIG. 1Aadditional modifications in the basic structure such as the use of thebinder form in which the structure consists of photosensitivefracturable material dispersed in the softenable layer may also be used.In addition, an overcoated structure in which the photosensitivefracturable material is sandwiched between two layers of the softenablematerial which overlying a substrate is also included within the scopeof this invention.

The. member 10 is processed to form an image, generally by forming alatent image on or in layer 13 followed by development of the latentimage. Forming the latent image and development are typically carriedout in the substantial absence of ambient actinic radiation for theimaging member. As described in aforementioned copending application460,377 new U.S. Pat. No. 3,520,681, and others referenced herein, thelatent image may be formed by uniformly electrostatically charging layer13, for example, to a surface potential of from about 1- 60-200 volts,exposing said layer to an optical image and developing by dissolvingaway layer 12 with a solvent.

However, any suitable method of forming a'latent image on members hereofand then developing may be used. Other methods of forming a latent imageon member 10 are known in the art and include corona charging through astencil as shown in aforementioned application Ser. No. 483,675, orforming a latent image by the other means described therein where thefracturable material need not be photosensitive. Another mode ofoptically forming a latent image is to use a member comrising aphotoconductive soluble layer and fracturable material which need not bephotosensitive as more fully described in copending application Ser. No.553,837, filed May 31, 1966, now abandoned.

Also any suitable method to cause migration of particles to develop theimaging members hereof may be used including softening the softenablelayer, for example, with solvent vapor and/or heat to cause migration asmore particularly described in aforementioned copending applications460,377 now US. Pat. No. 3,520,681 and 483,675, and in copendingapplication Ser. No. 612,122, filed Jan, 27, 1967. Although layer 12 andnonmigrated areas of fracturable material, are not washed away in vaporand heat development, the image produced may be viewed by means ofspecial display techniques including, for example, focusing lightreflected from the member onto a viewing screen. Moreover, a liquidsolvent including electrically conductive liquids may at any timethereafter be applied to such an image to convert it into a solventwash-away image. It should be understood that the inventive processhereof may be used to form any layered configuration, binder orovercoated structure used for any purpose so long as the product isformed according to the description herein.

Referring now to FIG. 2, there is illustrated a donor layer 14 in theform of a continuous web advancing from supply roll 15 consecutivelypast donor loading station 16 and transfer station 18 to be wound ontotakeup roll 20 powered by motor 22.

At the transfer station 18 a suitable softenable layer 12 on a suitablesubstrate 11 as described in relation to FIG. 1A advances from supplyroll 28to join with the particle loaded donor and the two members areadvanced together between pressure rolls 30 and 36. The two members arestripped apart as layers 11 and 12 are advanced around guide and tensionroller 31. Layers 11 and 12, layer 12 having picked up particles fromthe donor, are then advanced past fuser 33 to takeup roll 32 powered bymotor 34.

Donor 14 may be any suitable web material, such as a metal or a plastic,coatable with particulate material, alternatively, in softenablematerial, which by pressure contact with a softenable layer or asubstrate transfers a substantial portion of said carried particulatematerial to said softenable layer or substrate. Preferred donors for useherein, because of their ability to be uniformly coated with particulatematerial, their mechanical strength either alone or on asupportingsubstrate and their ability to transfer said material to layer 12according to this invention, have been foundto be various film formableplastics, a partial listing of which is found in copending applicationSer. No. 598,279, filed Dec. 1, 1966. Mylar film is found to beespecially preferred for donor 14 because it is flexible, dimensionallystable, in soluble in many solvents and releases particulate material ina pressure transfer step.,

At donor loading station 16, donor 14 is coated by any suitable methodto uniformly coat on the donor, particulate material tobe subsequentlylayered onto the surface of the softenable layer 12. Particulatematerial may conveniently be deposited onto the donor in a uniformlydistributed releasably adhering layer by a wide variety of techniquesincluding vacuum evaporation such as disclosed in copending applicationSer. No. 423,167, filed Jan. 4, 1965, now abandoned, running the donorthrough a quantity of particulate material, powder cloud techniques,wiping the material on the donor, cascading or dusting material over thedonor, for example, as described in copending application 460,377, nowUS. Pat. No. 3,520,681, applying it by various brushing techniques,examples of which are described in Vogt US. Pat. No. 3,375,806, ordepositing a uniform layer of particles by the migration imaging processdescribed in the aforementioned copending applications, for example byvacuum evaporating selenium on a softenable layer and charging,uniformly exposing and liquid solvent developing to form a layer ofselenium particles on donor 14.

However, it is found to be preferred herein in order to provide the mostuniform distribution of particulate material on the donor to dispersethe particulate material in a liquid vehicle to form a slurry ordispersion which may be applied to the donor by any of the well knownconventional painting or coating methods, including spray, drawdown,flow coating, knife coating, electrode coating, coating by uniformlycharging the donor and causing charged particles in a tank to adhere tothe web, for example as described in Mayer US. Pat. No. 2,877,133, Mayerbar drawdown, dip coating, reverse roll coating, spraying in an electricfield and so on. This technique of dispersing the particulate materialin a liquid vehicle and then coating on the donor, besides providing fora very uniform coating is also particularly well adapted to the coatingprocess herein since many of the lilquid vehicles used in coating may besolvents for or otherwise might, tend to degrade softenable'layer 12,which thus prohibits the use of such dispersion or slurry coatingtechniques to directly coat layer 12. Also, such direct coatingtechniques would not fix or at least partially fix the particulatematerial to layer 12, which is a desired end result of this inventionand is accomplished hereby 'due to the pressure transfer step.

For some particulate fracturable material especially photosensitivephthalocyanine particles, it is found that a small amount of softenablematerial on the phthalocyanine, as it resides on the donor prior totransfe r,'optimizes transfer of the particles from the donor to thesoftenable layer of members hereof. The softenable material to be coatedwith the particulate material may, in the preferred liquid vehicledispersion coating method described above, conveniently be incorporatedin the dispersion by employing a solvent for the incorporated softenablematerial as at least part of the dispersion liquid vehicle.Alternatively, a softenable layer may be formed on the donor and thenloaded with particles which may be embedded in the softenable layer bypressure or softening the softenable layer. The amount of softenablematerial in the dried layer of particles on the donor prior to transferto softenable layer 12, may just be thick enough, preferably from about1 to about 5 microns, for preferred uniformly dense, transfer results;to cause embedding of particles in the softenable material or may bethick enough, up-to a maximum of about 2 microns, for preferred transferresults, to cover a monolayer of particles or to provide a matrix fordispersed particles. At transfer station 18, typically, substantiallyall of the'particle layer on the donor, alternatively with softenablematerial, is stripped therefrom and transferred to a softenable layercoated on a substrate or as will be described to a sub strate.

FIG. 1A is illustrative of an imaging member, formed by the invention,after softenable layer 12 has been contacted with a particle loadeddonor; FIG; 1B is illustrative of an imaging member after softenablelayer '12 has been contacted with a donor that carried layer 13comprising a monolayer of particles just covered by softenable materialwhich is shown after transfer to layer 12; FIG. 1C is illustrative of animaging member after softenable layer 12 has been contacted with a donorthat carried a layer of softenable material just thick enough to causeembedding of particles therein, shown after transfer to layer 12; FIG.ID is illustrative of an imaging member after softenable layer 12 hasbeen contacted with a donor that carried layer 13 comprising a layer ofsoftenable material containing dispersed particles, which is shown aftertransfer to layer 12; and FIG. IE is illustrative of an imaging memberafter substrate 11 has been contacted with a donor that carried layer 13similar to layer 13 in FIG. 1D.

In the preferred particle-liquid dispersion, alternatively incorporatinga softenable material, mode of loading the donor, the dry weight ratioof solids, i.e. particles, alternatively with softenable material/liquidvehicle for suitable particle placing results according to thisinvention is found to vary between about 1/80 to about l/l, with apreferred range being from about 1/40 to about l/l.

For dispersions containing relatively large amounts of liquid forexample approaching the H80 figure, it is found that it becomesincreasingly difficult to coat to form a uniform layer of particles onthe donor upon drying, in that there is an increasing tendency for thedeposition of particles to be blotchy with open areas with no particles.Also, with these larger amounts of liquid it becomes increasinglydifficult to coat the dispersion, especially by simple 'draw coatingtechniques, to a sufficient thickness to produce a sufficiently denselayer of particles on the donor which is needed to produce by thisinvention a sufficiently dense particle layer on an imaging memberpreferred to give adequate density and contrast to the developedmigration images produced on the members hereof.

For dispersions containing relatively small amounts of liquid, forexample, in the area of the 1/ l figure, it is found that if the solidsconsist solely of particles, the particle layers deposited on the donorafter drying have a tendency to crack by the time they are transferredaccording to this invention. Generally for these lower liquid contentdispersions it has been found to be preferred to add softenable materialto the particle-liquid mixture. Of course, in this alternative theliquid should be a solvent for the particular softenable material added.

A preferred weight ratio range of particles/softenable material is fromabout 6/1 to about l/12. The dispersions with a relatively large amountof particles typically produce imaging members of the type illustratedin FIGS. 1A, B and C while dispersions with relatively larger amounts ofsoftenable material, i.e., ratios from about 3/1 or 2/ l to about I/ l 2approach or assume the character of binder layers more particularlydescribed in copending application Ser. No. 634,757, filed Apr. 28,1967, and illustrated as layers 13 in FIGS. 1D and IE.

As illustrated in FIG. 1D, this binder type layer may be transferredfrom the donor on which it is formed to a softenable layer 12 on asubstrate. Alternatively, the binder layer may be transferred by thisinvention from the donor on which it is formed directly to substrate 11to form a binder imaging member as illustrated in FIG. 1E. Thisalternative mode of forming a binder layer may be distinctly preferred,for example, where the solvent used in a particular particlesoftenablematerialliquid solvent dispersion would dissolve or otherwise degradesubstrate 11 if directly coated thereon, but not a donor whereon thedispersion could be coated and the solvent evaporated to form a binderlayer which may then be transferred, by this invention, to the substrate11.

Besides incorporating softenable material in the particle dispersioncoated on the donor, softenable material may be added to particlesloaded on a donor by dip, draw, roll or otherwise coating a particleloaded donor with softenable material dissolved in a solvent, preferablyin a dry weight ratio of softenable material/solvent of from about 1/80to about l/l and optimumly from about N40 to about l/l'.

Also, in solvent liquid wash away development, described for example incopending application 460,377, now US. Pat. No. 3,520,681, thedevelopment time may be purposely shortened somewhat to leave a smallamount of softenable material remaining behind with the migratedparticles. The particles in the softenable material may then betransferred to a softenable layer on a substrate to fabricate theparticle layer of a migra tion imaging member.

When loading and transferring only particles, any suitable thickness ofparticulate material may be coated on the donor at station 16, but toconstruct the layered configuration illustrated in FIG. 1A, preferredparticulate material thicknesses on donor 14, for uniform, densetransfer of particles to a softenable layer range from about 0.5 toabout 5.0 microns. FIG. 1B and 1C layer 13 preferred thicknesses rangefrom about 0.01 to about 2.0 microns, while FIG. 1D and 1E preferredthicknesses range from about k to about 16 microns. After loading atstation 16 the donor advances to transfer station 18. During thisinverval, the liquid vehicle used in loading the particulate material onthe donor may be evaporated to the desired degree to optimize thetransfer of material at station 18. If the liquid vehicle used inloading is a solvent for layer 12, then it is found to be preferred tosubstantially evaporate off the liquid before the donor reaches thetransfer station 18. It is found in certain applications of theinvention that if a small amount of a vehicle, which is a solvent forlayer 12, remains on the particulate material at transfer, this vehiclemay soften and tackify layer 12 to actually enhance the acceptance ofparticuate material by said layer. Layer 12 may also be softened orotherwise treated in the region of travel between supply roll 28 andpressure roll 30 to render it more receptive to pickup of particles,alternatively with softenable material, from the donor.

If the interval between stations 16 and 18 is long enough, evaporationinto the ambient atmosphere is sufficient, but for high speed operationsevaporation may be accelerated by the use of conventional techniquessuch-as heating, forced air and combinations thereof.

At particulate material transfer station 18 the material loaded on thedonor is transferred from the donor to softenable layer 12 which ismoved intopreferably non'slipping pressure contact with the loaded donor14. The two layers are pressed together between pressure rollers 30 and36.

Any suitable pressure to effect uniform transfer of the particles fromthe donor to layer 12 may be used. For example, for the transferapparatus embodiment illustrated, a force from about 10 to about poundsper linear inch of roller for about 2 inch diameter rollers with thelayers 12' and 14 advancing at about 1 /2 inches/second was found toeffect excellent transfer.

Of course, it will be appreciated that a flat donor may be pressedagainst a plate-like imaging member to effect the deposition of theparticulate material onto and into the softenable layer in a pieceworkoperation as contrasted to the continuous operation illustrated in FIG.2. Pressures preferred for highest quality particle placing are found tofall in the range of from about 80 to about 1,100 psi.

In addition to pressure, it was generally found to be preferred toeffect the pressure contact when the temperature of layer 12 was heatedto a temperature between about 50C. and about 200C. and optimumlybetween about 50C. and about 150C. It is thought that the tackinessimparted to layer 12 at these temperatures enhances the transfer ofparticles. Employing a heated roller 30 heated to a temperature in theabove stated ranges is found to be a preferred mode of heating layer 12because of its convenience and because of the excellent resultanttransfers of particulate material.

Softening layer 12 by exposure to solvents or vapors of a solvent forlayer 12 is also found to be suitable.

Any suitable method of stripping apart layers 12 and 14 may be used. Itwas found to be preferred after pressure contact between layers 12 and14 to cool layer 12 to around room temperature such as between about 10and 30C. before the two layers are stripped away at roller 31. Suchcooling enhances the ability of layer 12 to more completely receiveparticulate material from donor 14.

After stripping, layer 12 with particulate material contained fixedtherein advances past fixing station 33 and on to takeup roll 32.

Fixing at station 33 is found to be optional but preferred in someembodiments hereof, to cause the particulate material to become morefirmly adhered'to layer 12, to prevent offset to adjacent layers whenrolled on takeup roll 32. Heat and vapor fixing and combinations thereofare found to be suitable.

Vapor fixing the vapors of strong solvents for layer 12 are found tocause migration and dispersing of particulate material in layer 12,after being deposited as a layer contiguous the free surface of layer12, some par-.

ticles dispersing to distances up to about 2 microns from the freesurface of layer 12 to form a binder type imaging member.

The following Examples further specifically define the present inventionwith respect to the particle placing system hereof. The parts andpercentages are by weight unless otherwise indicated. The Examples beloware intended to illustrate various preferred embodiments of thisinvention. 3

EXAMPLE I A dispersion of particulate material in a liquid vehicle isprepared by ball milling together in a 2 ounce jar on a paint shaker forabout 5 hours, about one part of X-form metal-free phthalocyanine, forexample prepared as disclosed in Byrne et al. U.S. Pat. No. 3,357,989;about parts of a long chain saturated ali-' phatic hydrocarbon liquid,boiling point 315350F. available under the designation Isopar G from theHumble Oil Co. and about 150 parts of stainless steel shot. After thismixing, about 30 additional parts of Isopar G are added followed byabout 5 minutes of shaking. The resultant dispersion is coated onto anabout 4 mil thick Mylar film using a Bird applicator and allowed to dryin the ambient air to form an about one 12 micron layer of X-formmetal-free phthalocyanine uniformly deposited on the Mylar film.

A softenable layer is deposited on an aluminized Mylar film by coatingwith a Bird applicator about a 40% solution of Piccopale SE, a petroleumhydrocarbon resin available from Pennsylvania Industrial Chemical Corp.,in xylene to form about a 2 micron thick, dried layer of the softenablematerial on the aluminized Mylar.

The loaded donor and the softenable layer are then pressure rolledtogether usingapparatus simmilar to that shown in FIG. 2 at a rate ofadvancement of the two layers of about 1% inches per second with a forceon about 2 inch diameter pressure rollers of about 60 pounds per linearinch, with the temperature of the softenable layer at about C. Afterthis pressure contact the two laminated layers are allowed to cool toabout room temperature whereupon the two layers are separated to causetransfer of the particulate material from the donor to layer 12.

After separation v or stripping, coated layer 12 is treated with thevapor from trichloroethylene solvent available under the trademarkFLO-SET from Xerox Corpqfor about 5 seconds "and then dried for about 5minutes at about 50C. before being stored.

Dense images with resolutions greater than 25 line pairs/millimeterresult, using the imaging member produced in this Example processed asdescribed'in the aforementioned copending application Ser. No. 460,377.

EXAMPLE [I Example I is followed except that the donor is flexible brasssheet instead of Mylar film..

EXAMPLE III Example I is followed except that the softenable layer isformed by coating about a 20% solution of Amberol ST-137X, an unreactivephenol formaldehyde type resin available from Rohm and I-IaasCo., inxylene.

EXAMPLE IV Example I is followed except that the softenable layer isformed by coating about a 20% solution of Staybelite Ester 10 in xylene.

EXAMPLE V Example I is followed except that the'resultant particulatematerial comprises a trimix of about 50% X-form metal-freephthalocyanine, about 32% Watchung Red B and about 18% of a yellowpigment prepared as described in application Ser. No. 421,281, filedDec. 28, 1964, now abandoned.

EXAMPLE VI A dispersion is made up of about three parts of X- formmetal-free phthalocyanine, prepared as described in Byrne et al. U.S.Pat. No. 3,357,989 about nine parts of a polystyrene-vinyl toluenecopolymer available under the designation Piccotex 100 from PennsylvaniaIndustrial Chemical Corp., and about 40 parts of xylene. The dispersionis ball milled on a paint shaker in a 4 ounce jar with about 20 parts ofA; inch steel balls for about 2 hours and then sonically dispersed forabout 5 minutes just prior to coating.

The dispersion is draw down bar coated onto Plestar polycarbonate filmfrom Ansco Div. of General Aniline and Film Corp., and dried in air togive a thickness of about 2 microns.

A softenable layered substrate is then prepared by roll coating about a2 micron layer of Staybelite Ester 10 on Mylar film having a thintransparent aluminum coating.

The Stabelite softenable layer is then surface softened by wiping itonce with a cloth soaked with Freon 1 l3, and placed against thephthalocyanine coating on Plestar and the two members are passed throughpressure roller subjected to a force of about 30 lbs/linear inch ofroller, the rollers heated to about lC.

After cooling to about room temperature, the two members are peeledapart, to transfer the phthalocyanine binder layer to the Staybelitesoftenable layer.

The member is imaged by uniformly electrostatically charging it to asurface potential of about +100 volts, exposing the charged member to apositive (dark characters on a lighter background) optical imageincluding line copy with exposure in illuminated areas of the memberbeing about 2 f.c.s., the light source being a tungsten lamp with acolor temperature of about 3,20OK.

The image is developed by immersing the member in cyclohexane liquidsolvent for the Piccotex 100 and the Staybelite for about 3 seconds toproduce a positive image of migrated phthalocyanine particles on thealuminized Mylar substrate corresponding to said optical image.

EXAMPLE Vll A dispersion coating solution is prepared by combining aboutgrams of elemental selenium alloyed with arsenic (2% by weight ofarsenic), about 5 grams of a custom synthesized copolymer ofhexylmethacrylate and styrene, about 13 grams of toluene, and millingwith flint balls in a size 000 ball mil jar for about 4 days.

After removing the milling balls, this solution is coated onto flexiblesheet brass with a Gardner Draw Coater using a /2 mil Bird applicator.

A substrate of aluminized Mylar is then placed against the selenium in abinder coating on the brass, while the coating is still tacky, and thetwo members are passed through pressure rollers subjected to a force ofabout 30 lbs/linear inch. of roller, the rollers heate to about l00C.

After cooling to about room temperature, the two members are peeledapart, to transfer the selenium in a binder layer to the aluminizedMylar.

The member produced is imaged by uniformly electrostatically charging itto a surface potential of about +800 volts, exposing it to an opticalimage with exposure in illuminated areas being about 70 f.c.s., anddeveloping by immersing the member in lightly agitated trichloroethyleneliquid for a few seconds, to produce a positive image of a positiveoriginal. For example, if a positive transparency is used as theoriginal, the photosensitive particles comprising selenium migrate inthe imagewise unexposed areas to produce a deposition pattern of darkerselenium, corresponding to the darker or colored areas of the positivetransparency, on the relatively lighter aluminized Mylar substrate toproduce a directly viewable image and one which may be 6 used as aprojection transparency.

Although specific components and proportions have been stated in theabove description of preferred embodiments of the particle placingmethod hereof, other suitable materials as listed herein may be usedwith similar results. In addition other materials may be added to themixture or variations may be made in the various processing steps tosynergize, enhance or otherwise modify the systems properties. Forexample, in the interval as donor 14 advances between rollers 30 and 31,external cooling means other than ambient air may be used to acceleratecooling. Also a release agent may be coated on donor 14 before beingloaded to facilitate transfer of loaded material at transfer station 18.Also, softenable materials used herein may be modified by addingcoloring agents such as dyes or by adding plasticizers or moisture andother proofing" agents, as known to those skilled in the art.

it will be understood that various other changes in the details,materials, steps and arrangements of parts which have been hereindescribed and illustrated in order to explain the nature of theinvention will occur to and may be made by those skilled in the art upona reading of this disclosure and such changes are intended to beincluded within the principle and scope of this invention.

What is claimed is: Y

1. A migration imaging process comprising:

1. providing an imaging member made by the steps a. loading onto a donorsurface asubstantially uniform layer of particles, said layer consistingessentially of particles having average particle size in the rangebetween about 0.01 and about 2.0 microns, with said layerof particles ofthickness not greater than about 5.0 microns;

b. providing on a supporting substrate a receiver layer of substantiallyelectrically insulating softenable material, of thickness in the rangebetween about /2 and about 16 microns, said softenable material capableof having its resistance to migration of said particles decreasedsufficiently to allow migration of said particles through saidsoftenable material toward said substrate;

c. uniformly pressing the loaded donor surface in non-slipping contactagainst the surface of the softenable layer by advancing said loadeddonor and said softenable layer at the same rate in the same directionbetween pressure rollers with pressures in the range between about andabout 1,100 psi; and I d. separating said donor surface and saidsoftenable layer, thereby transferring a uniform layer of particles tothe softenable layer whereby a fracturable layer of particles isembedded at the surface of the layer of softenable material;

2. forming an electrical latent image on said imaging member formed bythe process of step 1;

3. developing said latent image by decreasing the resistance of thesoftenable material to migration of the particles at least sufficient toallow imagewise migration in depth of the particles toward thesubstrate.

2. A method according to claim 1 wherein said softenable layer is athermoplastic, and at least one of said pressure rollers is heated tobetween about 50C. and about 200C.

3. A method according to claim 2 wherein after said heat-pressure stepthe softenable layer is cooled to be- 16 tween about 10C. and about C.before the separat- 6. A method according to claim 5 wherein said phomgP- toconductor is selected from the group consisting of 4. A methodaccording to claim 1 wherein said particles comprise an electricallyphotosensitive material. 5. A method according to claim 4 wherein saidparti- 5 "mes, and mlxtures thereofcles comprise a photoconductor.

materials comprising amorphous selenium, 'phthalocya-

1. A MIGRATION IMAGING PROCESS COMPRISING:
 1. PROVIDING AN IMAGINGMEMBER MADE BY THE STEPS OF A. LOADING ONTO A DONOR SURFACE ASUBSTANTIALLY UNIFORM LAYER OF PARTICLES, SAID LAYER CONSISTINGESSENTIALLY OF PARTICLES HAVING AVERAGE PARTICLE SIZE IN THE RANGEBETWEEN ABOUT 0.01 AND ABOUT 2.0 MICRONS, WITH SAID LAYER OF PARTICLESOF THICKNESS NOT GREATER THAN ABOUT 5.0 MICRONS; B. PROVIDING ON ASUPPORTING SUBSTRATE A RECEIVER LAYER OF SUBSTANTIALLY ELECTRICALLYINSULATING SOFTENABLE MATERIAL, OF THICKNESS IN THE RANGE BETWEEN ABOUT1/2 AND ABOUT 16 MICRONS, SAID SOFTENABLE MATERIAL CAPABLE OF HAVING ITSRESISTANCE TO MIGRATION OF SAID PARTICLES DECREASED SUFFICIENTLY TOALLOW MIGRATION OF SAID PARTICLES THROUGH SAID SOFTENABLE MATERIALTOWARD SAID SUBSTRATE; C. UNIFORMLY PRESSING THE LOADED DONOR SURFACE INNONSLIPPING CONTACT AGAINST THE SURFACE OF THE SOFTENABLE
 2. FORMING ANELECTRICAL LATENT IMAGE ON SAID IMAGING MEMBER FORMED BY THE PROCESS OFSTEP 1;
 2. A method according to claim 1 wherein said softenable layeris a thermoplastic, and at least one of said pressure rollers is heatedto between about 50*C. and about 200*C.
 2. forming an electrical latentimage on said imaging member formed by the process of step 1; 3.developing said latent image by decreasing the resistance of thesoftenable material to migration of the particles at least sufficient toallow imagewise migration in depth of the particles toward thesubstrate.
 3. A method according to claim 2 wherein after saidheat-pressure step the softenable layer is cooled to between about 10*C.and about 30*C. before the separating step.
 3. DEVELOPING SAID LATENTIMAGE BY DECREASING THE RESISTANCE OF THE SOFTENABLE MATERIAL TOMIGRATION OF THE PARTICLES AT LEAST SUFFICIENT TO ALLOW IMAGEWISEMIGRATION IN DEPTH OF THE PARTICLES TOWARD THE SUBSTRATE.
 4. A methodaccording to claim 1 wherein said particles comprise an electricallyphotosensitive material.
 5. A method according to claim 4 wherein saidparticles comprise a photoconductor.
 6. A method according to claim 5wherein said photoconductor is selected from the group consisting ofmaterials comprising amorphous selenium, phthalocyanines, and mixturesthereof.